[NTLUG:Discuss] Permissions to CDROM

[Mark Bickel]

> From discuss-admin at ntlug.org Thu Feb 15 21:20 CST 2001
> Date: Thu, 15 Feb 2001 21:15:24 -0600
> From: Randall Gibson <wabbit at tvec.net>
> To: discuss at ntlug.org
> Subject: Re: [NTLUG:Discuss] Permissions to CDROM and Printer Issue
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> 
> Try :
> /dev/cdrom
> or,
> /dev/scd0   (For SCSI)
> 

> > when I try to run Grip (or 
> > any other similar program) I get "Unable to
> > open the cd device. Please make 
> > sure that you are using the correct device
> > (passed to the program with "-d") 
> > and that you have permission to access the
> > device."  Other programs just say 
> > "Permission Denied".  It doesn't happen when I
> > run the program as root.  
> > Where do I change the permissions?

Permissions are set for block devices in /dev.
Permissions for symbolic links are useless for this purpose. You
must change the permission for the block device itself, not the
symlink. /dev/cdrom is not a real device. It is a symbolic link to 
/dev/hdc or somesuch for ATA drives or
/dev/scd0 or somesuch for SCSI drives.
Note: the SCSI stuff is changed quite a bit in 2.4 kernel's /dev system.

For filesystems you can mount as root but give read/write and owner/group 
permissions to the mount and mountpoint according to your needs.
Permissions are set for mountpoints that mount at bootup in /etc/vfstab
man mount
man vfstab

Some distributions setup an automount daemon for removable media like
floppies and CDROMs - either autofs or amd (typically) so you don't
have to deal with all the mount/umount hassle. This is great for 
desktops where security is not a big issue. I don't recommend these for
servers. These are configured in /etc/amd/amd.conf or /etc/autofs.conf
(locations may vary) and in your /etc/rc.d/ runlevel scripts.

Mark.Bickel at ericsson.com